The WLM store folder is easily backed up. This folder is located in C, Users, "User Name" and is listed as Windows Live Mail. Just copy this folder to a flash drive or another partition, then when finished with the reinstallation, copy this folder back into the original location and let it replace the new WLM folder created when the reinstallation occurred.

Over past month the status came good or bad sometimes. Last week came the worst. I have uninstall the WLM and then re-install WLM 2012. The folders and setting don't need be changed and can be restored.

However, just within same day after re-install, this happen again but less frequent. I think there should be some problem but I dunno what's it.

[QUOTE][This is known to happen if you have too many Temporary Internet Files.

Are you fully up to date at Windows Update? In particular, do you have IE9? If you type shell:cache into the start search box and press Enter, you should see an Explorer window open at the TIF folder. Right-click on that folder in the navigation pane and select Properties.
What are the numbers for Files, Folders and Size on disk?
How does that Size on disk compare with the specified size at Control Panel > Internet options > General > [Browsing history] Settings > Disk space to use?
If you're using IE9, a simple cache clearance may help:
Go to Control Panel > Internet Options and click Delete...
Select the top two options and click Delete.
Re-launch Windows Live Mail and see whether the problem still exists.
If this doesn't help, creating a new, empty TIF folder might.
Under Internet Options, click the Settings button under Browsing history and then Move folder.
Choose a location (e.g. somewhere in your user profile that's not being backed up)
Log off and on again to complete the move before launching WLMail and testing.
Otherwise, you might have to resort to brute force to get rid of your TIF.
/QUOTE]
Jerry